The continuous increase in fuel prices and stricter regulations on emissions have pushed the attention of truck designers into new areas to provide more fuel effcient solutions. The flow in the front wheelhouse is a relatively unexplored area, compared to studies on the shapes of the cabin, roof and trailer. However, it is known that the underhood is responsible for almost half of the total aerodynamic drag, with the front wheelhouse being one of the contributors. As a step towards improving the flow in the underhood, this thesis, performed at DAF Trucks N.V., focussed on the identiffication of aerodynamic phenomena in the front wheelhouses of heavy trucks using CFD simulations.